New Icosahedron style proof of concept

So I made an icosahedron out of BB ply. It involved a lot of sanding.

So, turns out sanding precisely is hard. I built a series of small boxes to hold the piece at the correct angles, and it got really close to good, and then I said “oh I’ll just clean it up a little freehand.” Bad plan.

Next time (if I do a next time) I’ll get more serious about sanding jigs to get it exact.

Still, as a proof of concept, this is kind of cool.


When faceting stones folks use a rig like this to swing the stone at a precise place and angle and to be certain not to bring it too far.

What you are doing is a bit different so you would have to make your own rig, but it would be clean and accurate. If you wander down that rabbit hole there is a similar much older design that diamond cutters used to use that would be easier to build but harder to use.


Very cool. After all that sanding I can still see two fingers.


Oh my! You do like pushing of envelopes! :grinning:


Nope no fingers. It was layered. I sliced a 1” tall icosahedron model into 1/8” layers in sketchup and cut them, with three registration holes for brass pins.

So this is solid ply. If you look closely you can see the three pins in one of the faces.

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Okay, one finger and a thumb… :wink:



Looks cool.

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I made a quick Blender of the older stone cutting tool layout. Different geometry backs (pentagon,hexagon, square, etc) and setting the height of the shelf to get the correct angle. They used dop wax to hold the stone in place but you might have a different method,

Sorry was posted in wrong thread origanally


So do you feel this technique has more potential than a hollow version with sanded fingers?

If you want your own wooden dice perhaps?

What’s wrong with hollow dice?

At six inches on a side perhaps but a half inch on a side not so much

Depends. Do you want gaps? There’s no real way to sand angled fingers down to have zero gaps. If you overshoot by even a tiny bit you’ll start to see space between the finger and the other face.

I was hoping for a truly solid wood icosahedron. I think it could be done but I have to find a more precise way to sand the angles and depth so that I get it just right.

I think if I upped the scale to be 2” I might be able to get a more accurate result.


Working up to it in grits on a horizontal disc sander would be the best way to go, but that’s not very practical for occasional use. Perhaps a palm sander clamped in a vise?

I think you could get very precise with the getup I sketched with the best point that the finished face will be more flat than just holding it could do.

Yeah, the grinding rig helps if you’re patient enough and careful enough. I never was. I took an evening class on faceting garnet. Made me appreciate faceted stones MUCH more by the time I was done. It also saved me lots of money on faceting equipment that I knew I’d never even look at after the class finished.


That is the old-fashioned system used for perhaps a hundred years, the modern setups let you dial in the distance and angle like a micrometer for each facet. However, no matter the technique, if you need a microscope to judge how well the job was done, plus it is an exercise in math to tell you which angles work best for each material. the effort of extra perfection will be largely lost on over 99% of those who see it.

Yep. Old fashioned enough to use wax to hold the stone in place. I found out the hard way that you could shift the stone off of the centerline by pressing down too hard. I found that was not the part of the jewelry making hobby I should invest my time in. I stuck with soldering and casting metals for my efforts. Buying a faceted stone was the best way, meaning the least frustrating way to work.

Yes but of course now that you know you can look with a loop and see bad cutting mistakes already done for you. I did my own cabochons and a lot of carving and inlay. I did do a lion head with diamonds, but I embedded white gold and had an expert set them, but otherwise did little with faceted stones.

Yes. I used my embarrassing experience to help pick the best of a group of ruby post earrings for my wife on a business trip to Thailand many years ago. I could see on the table the effect of one facet being ground too far. I sympathized with the faceter, but bought the better stones.

Sadly, I had to quit most of the jewelry making when I moved to the east coast and couldn’t afford a home with a basement. It’s no good lighting the torch up in the kitchen, even if I promised to make something nice for SWMBO. Just part of the long journey to playing with the Glowforge.